1. Field of the Invention
The present invention relates, in general, to a heat pump system and, more particularly, to a heat pump system that is capable of performing a heating operation and a cooling operation at the same time or selectively performing a heating or a cooling operation.
2. Description of the Prior Art
As well known to those skilled in the art, a general heat pump system is constructed by sequentially connecting a compressor, a four-way valve, a first heat exchanger (an indoor heat exchanger), two expansion valves, a second heat exchanger (an outdoor heat exchanger) and the four-way valve to each other by a conduit and additionally connecting the four-way valve to the compressor by a suction conduit, thus forming a refrigeration circuit.
In a heating operation, in a state where the four-way valve is manipulated to allow refrigerant to flow toward the first heat exchanger, there is repeated a cycle in which high temperature and high pressure refrigerant compressed in the compressor is condensed in the first heat exchanger and simultaneously radiates condensation heat to generate hot water or heat room air for the heating of a room or drying of articles, the compressed refrigerant liquid is expanded in the expansion valve and evaporated into low temperature and low pressure refrigerant gas by means of the ambient air in the second heat exchanger functioning as an evaporator, and the refrigerant gas is sucked into the compressor.
On the other hand, in a cooling operation, in a state where the four-way valve is manipulated to allow refrigerant to flow toward the second heat exchanger, there is repeated a cycle in which high temperature and high pressure refrigerant compressed in the compressor is condensed in the second heat exchanger functioning as a condenser, the condensed refrigerant liquid is expanded in the expansion valve, the expanded refrigerant is evaporated into low temperature and low pressure refrigerant gas in the first heat exchanger and simultaneously absorbs evaporation heat to generate cold water or cool room air for the cooling of a room or refrigeration of articles, and the evaporated refrigerant is sucked into the compressor.
However, in the conventional heat pump system, since the heating or cooling operation is selectively performed by utilizing the condensation or evaporation heat of the first heat exchanger and discarding the condensation or evaporation heat of the second heat exchanger, the effective utilization of heat is almost impossible. Additionally, when a heating operation and a cooling operation are desired to be performed at the same time, a pair of heat pump systems must be installed, thereby complicating the construction of a facility, occupying a great deal of installation area and increasing facility costs.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a heat pump, which is capable of performing a heating operation and a cooling operation at the same time or selectively, thereby effectively utilizing heat, simplifying the construction of a facility and reducing the installation area of the facility.
In order to accomplish the above object, the present invention provides a heat pump system, comprising: a base heat pump system constructed in such a way that a compressor, a four-way valve, a first heat exchanger, two expansion valves, a second heat exchanger and the four-way valve are sequentially connected to each other by first, second, third, fourth, fifth and sixth conduits, and the four-way valve is additionally connected to the compressor by a suction conduit; a third heat exchanger disposed on an eighth conduit, the eighth conduit connecting a seventh conduit, connected to the fourth conduit at its both ends, to the portion of the fourth conduit situated between two junction points of the fourth and seventh conduits; a fourth heat exchanger disposed on a ninth conduit, the ninth conduit connecting the second conduit to the portion of the eighth conduit situated between the third heat exchanger and a junction point of the fourth and eighth conduits and being provided with an additional expansion valve on its portion situated between the fourth heat exchanger and a junction point of the eighth and ninth conduits; a tenth conduit connecting the sixth conduit to the portion of the ninth conduit situated between the additional expansion valve and the junction point of the eighth and ninth conduits; an eleventh conduit connecting the portion of the eighth conduit situated between the junction point of the eighth and ninth conduits and the junction point of the fourth and eighth conduits to the tenth conduit; and a twelfth conduit connecting the portion of the ninth conduit situated between the fourth heat exchanger and a junction point of the second and ninth conduits to the portion of the tenth conduit situated between a junction point of the tenth and eleventh conduits and a junction point of the sixth and tenth conduits.